1. Field of the Invention
This invention relates to aqueous dispersions of alkaline earth metal soaps and/or alkaline earth metal resin soaps for deinking printed wastepaper and to the use of aqueous dispersions containing A. alkaline earth metal salts of C.sub.6-22 carboxylic acids and/or resinic acids and B. alkoxylated C.sub.6-22 oxoalcohols and/or certain alkali and/or alkaline earth metal alumimo silicates for deinking printed wastepaper.
2. Discussion of Related Art
Today, wastepaper is used in large quantities for the production of, for example, newsprint and sanitary paper. The quality of these types of paper are determined by their lightness and color. To be able to produce high-quality paper, the printing inks have to be removed from the printed wastepaper. This is normally done by deinking processes essentially comprising two steps, namely:
1. disintegrating the wastepaper, i.e. fiberizing in water in the presence of the chemicals required for detachment of the printing ink particles and PA1 2. removal of the detached printing ink particles from the fiber suspensions. PA1 A. alkaline earth metal salts of C.sub.6-22 carboxylic acids and/or resinic acids and PA1 B. C.sub.6-22 oxoalcohols alkoxylated with 2 to less than 6 mol C.sub.2-4 alkylene oxides and/or alkali metal and/or alkaline earth metal alumino silicates corresponding to general formula I EQU 0.7-1.5 cat.sub.2/n O.Al.sub.2 O.sub.3.0.8-6 SiO.sub.2 PA1 in which cat represents alkali metal and/or alkaline earth metal cations and n is the valency of the alkali metal and/or alkaline earth metal cations. PA1 A. alkaline earth metal salts of C.sub.6-22 carboxylic acids and/or resinic acids and PA1 B. C.sub.6-22 oxoalcohols alkoxylated with 2 to less than 6 mol C.sub.2-4 alkylene oxides and/or alkali metal and/or alkaline earth metal alumino silicates corresponding to general formula I PA1 in which cat represents alkali metal and/or alkaline earth metal cations and n is the valency of the alkali metal and/or alkaline earth metal cations, PA1 A. alkaline earth metal salts of C.sub.6-22 carboxylic acids and/or resinic acids and PA1 B. C.sub.6-22 oxoalcohols alkoxylated with 2 to less than 6 mol C.sub.2-4 alkylene oxides and/or alkali metal and/or alkaline earth metal alumino silicates corresponding to general formula I EQU 0.7-1.5 cat.sub.2/n O .Al.sub.2 O.sub.3.0.8-6 SiO.sub.2 PA1 in which cat represents alkali metal and/or alkaline
The second step can be carried out by washing or flotation (Ullmanns Encyclopadie der technischen Chemie, 4th Edition, Vol. 17, pages 570-571(1979). In flotation, which utilizes the difference in wettability between printing inks and paper fibers, air is forced or drawn through the fiber suspension. Small air bubbles attach themselves to the printing ink particles and form a froth at the surface of the water which is removed by savers.
The deinking of wastepaper is normally carried out at alkaline pH values in the presence of alkali metal hydroxides, alkali metal silicates, oxidative bleaches and surfactants at temperatures in the range from 30.degree. to 50.degree. C. Soaps and/or fatty alcohol polyglycol ethers are often used as surfactants which are responsible for the detachment and separation of the printing ink particles (Ullmanns Encyclopadie der technischen Chemie 4th Edition, Vol. 17, pages 571-572 (1979). DE-OS 31 44 387 describes a process for regenerating wastepaper using calcium soap solutions. The calcium soaps are made from fatty acids which, in a first step, are converted with sodium hydroxide into the corresponding alkali metal soaps. The alkali metal soaps are then reacted with calcined lime or milk of lime at temperatures of 50.degree. to 90.degree. C. to form the corresponding lime soaps. Since the capacity of the calcium soaps obtained to act as collectors for printing inks decreases with time, it is absolutely essential to add the lime soaps unchanged, i.e. immediately after their production, to the fiber suspensions before flotation.
In addition, it is known from DE 37 02 978 that fatty acids and/or resinic acids are suitable for the deinking of printed wastepaper in the form of their alkaline earth metal salts finely dispersed with dispersants in an oil-in-water dispersion which is liquid at normal temperature. The dispersants used are nonionic and/or anionic surfactants, for example alkyl polyglycol ethers and/or iso-alkyl polyglycol ethers containing 8 to 22 C atoms in the hydrocarbon radicals and 6 to 30 mol ethylene oxide and/or alkyl sulfates and/or alkyl polyglycol ether sulfates containing 8 to 22 C atoms in the hydrocarbon radicals in the form of their alkali metal and/or amine salts. The use of the dispersions described in this patent produces a fine dispersion of the calcium soaps and/or calcium resin soaps in the paper fiber suspensions, so that good deinking results are obtained. However, these dispersions often form very stable foams during flotation so that foam inhibitors have to be added to the fiber suspensions.
The problem addressed by the present invention was to provide aqueous, storable, finely divided dispersions of alkaline earth metal soaps and/or alkaline earth metal resin soaps for the regeneration of wastepaper which would eliminate the need to add foam inhibitors before or during flotation.